Fuel Tank Leak

[easterly38]

We recently developed a small fuel tank leak. We have removed the tank, but need some advice from those who have actually dealt with this.

The fuel is diesel. The tank is aluminum. The small holes were caused by wear against the hull...33 years of it. There are also some spots with pitting on the outside, but they are not leaking.

Here's the plan. The tank exterior has been thoroughly cleaned. We intend to braise (sp?) the holes and the pitted areas. We would also like to coat the exterior with some sort of paint or sealant.

Any ideas? Are we going about this in a totally wrong fashion? Just looking for some help from folks who have actually dealt with this and their successes and failures.

Thanks in Advance, Brian

[DeepFrz]

Idea #1: Replace the tank.

Gee, I have no other ideas!

[Blue Stocking]

I'm with Frz on this one. 33 yrs--that tank has paid it's dues.

[Ziggy]

Idea #2: Replace the tank.

Even if you're successful fixing the leak, chances are another will open up. You don't want diesel in your bilge, do you?

A custom made aluminum tank is less expensive than you might think.

[Mark Zarley]

I agree with replacing the tank. That said I have 4- 200 gal tanks that developed pits (cavities) in the bottom(inside ) due to a mild acidic ( a bi-product of algae).I took a dremel to the bottom and drilled out the cavities ( the stuff was a wet powder) and filled the holes with JB weld. Then sanded the entire bottom and 2"up the sides and spread another layer of JB weld. The exterior of my tank was ok but JB should work on that also( your bottom must be laying in water or you need to mount it in neopreme with 4200 as the adhesive, this prevents condensation from laying between the tank and the contact point). Did some comparison tests with Marine Tex and JB was superior. Would still recomend replacement , but if you have more time than money this worked for me .

[easterly38]

Yes, the tank has paid its dues. Severe storms while sailing the Gulf, then Rita, Gustav, and Katrina. I just hope to get the old boat back on it's feet until the arterial bleeding of cash slows down to a mild gush. Then Maybe I can start making long-term improvements. Anyone else care to pipe in? You guys really came through when I pulled the engine and rebuilt the logs, could not have done it without you. Looking for that same help in this repair. (I'm not kidding, I did that job from advice from this forum!)

[guyfromiowa]

I bought my boat, a nice Newport 30 MKIII, because the fuel tank burst and flooded the bilge and cabin with diesel fuel. I bought the boat for less than the price of the nearly new GM20F. If the PO had replaced the tank instead of patching it with epoxy he'd still have the boat instead of selling it to the insurance company. Your call.

Guy

[easterly38]

Originally Posted by guyfromiowa

I bought my boat, a nice Newport 30 MKIII, because the fuel tank burst and flooded the bilge and cabin with diesel fuel. I bought the boat for less than the price of the nearly new GM20F. If the PO had replaced the tank instead of patching it with epoxy he'd still have the boat instead of selling it to the insurance company. Your call.

Guy

How is it possible for a fuel tank leak to flood the cabin? Aren't most tanks below the sole? (Maybe not, I'm not sure.) And then there is the bilge. How can a bilge be flooded? Broken? "Burst?" Mine leaks, (a little) it didn't blow up. I'm not sure what you are trying to say. I never mentioned repairing the tank with epoxy and I asked only for responses from others who had dealt with same issues. Not to be terse, but I'm not sure what to make of this response.

[easterly38]

Looks like I'll go with plan A and then plan B. I'm getting the tank braised (SP) for free. I'll let it ride a few months then have a new one fabricated. Thank goodness it is not a big job to remove/install it. I agree with you guys, 33 years is good 'nuff. Time for a new one.

[GordMay]

Originally Posted by easterly38

... I never mentioned repairing the tank with epoxy and I asked only for responses from others who had dealt with same issues. Not to be terse, but I'm not sure what to make of this response.

Guy recommends that epoxy patches, as mentioned by Mark (JB Weld), not be applied to fuel tanks. That's it.

[guyfromiowa]

Originally Posted by easterly38

How is it possible for a fuel tank leak to flood the cabin? Aren't most tanks below the sole? (Maybe not, I'm not sure.) And then there is the bilge. How can a bilge be flooded? Broken? "Burst?" Mine leaks, (a little) it didn't blow up. I'm not sure what you are trying to say. I never mentioned repairing the tank with epoxy and I asked only for responses from others who had dealt with same issues. Not to be terse, but I'm not sure what to make of this response.

Fair enough question. The factory put the fuel tank under the starboard quarterberth. Over time the tank corroded and a PO removed the tank and patched it with epoxy. The boat got blown away from the dock in a storm and heeled over in shallow water. The angle and the wind and wave action conspired with a nearly full fuel load to burst the tank where it had been patched. After that? Imagine the action inside a washing machine. Filled with diesel fuel.

IMHO if the tank had been well-made of epoxy/ply construction no harm would have come to the boat from a fuel leak. Corroded aluminum with a cheesy epoxy patch got me a good boat cheap. Also - the new tank is rotomolded HDPE in a custom mount.

Guy

[easterly38]

Guy,

that makes sense...but I sure never would have guessed that scenario!

Thanks for the clarification, BAB

[brankin]

I had a similar problem on my fuel tank(diesel,200 gal, aluminum, endeavour 43) and there was no way to get a new tank into the boat without cutting a hole in the side of the boat. My solution was to use an aircraft fuel tank sealant and do the repair inside the boat. I cleaned all the pits and etched the aluminum and then troweled on a uniform coat of sealant on the damaged skin and then applied a new piece of aluminum plate over the sealant. After the new skin was all done, I pressure tested the tank to 4 psi for several days to confirm the integrity of the repair.

http://www.flamemaster.com/TechnicalsPDF/cs3204.pdf

This is also the best way to seal your ports. I tried all the marine sealants and the port holes always leaked until I bedded the port hole with this product. BTW, it is about 3 times the price you will pay for something like 5200 but hey if it works, it is cheap.